Field
The embodiments are directed generally to calibrating devices under test, and specifically, to calibrating triaxis MEMS sensors by rotating the devices around a single axis.
Background Art
A triaxis MEMS sensor is a device that can sense its orientation relative to a given axis, for example the axis defined by earth's local gravitational field. More generally, a triaxis MEMS sensor can measure excitation in at least three orthogonal directions.
Within a triaxis MEMS sensor, there can be multiple sense elements capable of sensing different physical inputs. These sensors that are capable of sensing multiple physical inputs are sometimes referred to as combination sensors. For example, a triaxis MEMS sensor could simply comprise a triaxis accelerometer and, therefore, be considered a three degree-of-freedom (DOF) system—one DOF for each dimension in physical space. If a triaxis gyroscope were combined with the triaxis acceleration sensor, it would be considered a six DOF system—three DOF for the triaxis accelerometer and three DOF for the triaxis gyroscope. It is also becoming common to combine a triaxis magnetometer with a triaxis gyroscope and a triaxis accelerometer to provide a MEMS sensor having sensitivity along nine DOF. Multi-DOF combination sensors can also encompass sensing inputs that are not as easily associated with spatial directions, such as pressure and temperature. With these additions, it is possible to construct ten and eleven DOF sensors.
As triaxis MEMS sensors appear in more and more devices, for example cell phones, laptops, tablet computers, video game controls, Segways, etc., the need for triaxis MEMS sensors will continue to increase. But calibrating triaxis MEMS sensors is a time-consuming process. The calibration units can only calibrate the number of triaxis MEMS sensors that fit on the testing head. For example, if a testing head can hold 8 triaxis MEMS sensors and it takes 3 minutes to run the calibration tests and 1 minute to load and unload the triaxis MEMS sensors onto the testing head, then even if the calibration unit runs for 24 hours/day, it can only calibrate 2880 triaxis MEMS sensors in a day.
Therefore, what is needed are systems and methods to efficiently calibrate numerous triaxis MEMS sensors. In addition, there is a need to be able to calibrate multiple DOF of a device under test using the same calibration unit or similar versions of that calibration unit.